1. Field of the Invention
The invention relates to an assembly error prevention member and a universal joint that incorporates the assembly error prevention member.
2. Description of the Related Art
A conventional universal joint is generally includes a yoke body having a cylindrical portion in which an axially-extending slit is formed and having a first tab and a second tab that face each other across the slit. A shaft is inserted into the cylindrical portion of the yoke body of the universal joint and then clamped by the cylindrical portion when a bolt is inserted into a bolt through-hole of the first tab and then tightened into a bolt hole of the second tab. A curved recess is formed at a given axial position on the outer peripheral face of the shaft, and during assembly, the bolt is inserted through the recess, whereby the shaft is set in its target position. According to this universal joint, if the bolt is inserted into the bolt through-hole before the shaft reaches its target position, the front end of the bolt contacts the shaft, which prevents the bolt from being tightened into the bolt hole of the second tab. This prevents the shaft from being fastened to the yoke body of the universal joint when the shaft is not in the target position.
However, the bolt may also be tightened into the bolt hole of the second tab if the front end of the shaft has not been inserted to the position of the bolt, and this results in an assembly error of the universal joint. To counter this, for example, Published Japanese Translation of PCT application No. 11-505917 (JP-A-11-505917) describes the use of a wire to block the inserted bolt when the shaft has not been inserted to the target position. Further, Japanese Patent Application Publication No. 60-11717 (JP-A-60-11717) describes the use of an edge of a plate to block the inserted bolt when the shaft has not been inserted to the target position. According to these technologies, however, because of the small area of contact between the wire and the front end of the bolt and the small area of contact between the plate edge and the front end of the bolt, the bolt cannot be reliably blocked.
On the other hand, Japanese Patent Application Publication 2006-226415 (JP-A-2006-226415) describes the use of a plate to block the inserted bolt when the shaft has not been inserted to the target position. According to this technology, the front end of the bolt contacts one face of the plate, and therefore, the area of contact between the plate and the front end of the bolt is large, and the bolt can be reliably blocked.
According to the assembly error prevention member described in JP-A-2006-226415, a first plate portion of the plate, which is fixed to the yoke body of the universal joint, is connected to a fourth plate portion of the plate, which is disposed in the slit of the cylindrical portion of the yoke body of the universal joint, via a second plate portion and a third plate portion of the plate, which are connected to each other in a folded-back form. Therefore, when the fourth plate portion is raised by the insertion of the shaft into the cylindrical portion of the yoke body, a specific portion of the second plate portion or a specific portion of the third plate portion may be largely lifted up. Thus, a universal joint incorporating the assembly error prevention member according to JP-A-2006-226415 requires a large space for installation and thus is difficult to mount in a vehicle.